The present invention relates to a seat-back frame for an automotive vehicle, and, more particularly, it is concerned with a seat-back frame reinforced by a tensile member extending diagonally from an upper corner to a lower corner.
External force applied to the seat-back frame for an occupant seat in an automotive vehicle, when vehicle collision takes place, is either in the back-and-forth direction to move the seat in the front-and-back direction, or in the sidewise direction that tends to deform it sidewise with the upper corner part of the frame as a load applying or pivotal point for the deformation.
With a view to preventing such deformation of the seat-back frame due to the lateral force, there have so far been contemplated various preventive measures such as, for example, reinforcing corner plates fixed onto each of the four corners of the seat-back frame by welding, etc., or a compression-resistant strut obliquely extended between one corner of the frame and the other opposite to the former. Of these preventive measures, to be effective, the reinforcing corner plates should be made sufficiently large in size, and the compression-resistant strut such as rod material should have such a large cross-sectional area as to attain sufficient reinforcement of the seat-back frame. As the result, the frame becomes disadvantageously heavy in weight.